Dust-counter.



E. V. HILL.

DUST COUNTER.

APPLICATION FILED FEB. 5. 1911.

1 NM *v \1 I I I f INVEN TOR.

2 ATTORNEY? EARL V. HILL, OF CHICAGO, ILLINOIS.

DUST-COUNTER.

Specification of Letters Patent.

Patented A11 6, 1918.

Application filed February 5, 1917. Serial No. 146,639.

To (all whom it may concern:

Be it known that I, Eanl. V. Ilium, a eiti- Zen of the United States, residing at lhi cago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in DustsCounters, of which the following is a sl iecification.

My invention relates more particularly to an apparatus for counting or approximating the number of particles of solid matter contained in a'given volume of air. T he instrument is useful in a variety of connections but was designed more particularly with re't'e rence tothe science of ventilation 'in' which it is important to know, among other things, the extent of contamination by solid partieles'ot' various kinds in the form of dust. The apparatus is further useful for the purpose of ascertaining the number of bacteria contained in a given quantity of air, a slight modification of the device being made for this purpose.

In the accompanying drawing I have shown and in the following specification de scribed in detail a pre terred :lt'orm otthe apparatus with attachments to be used for counting dust and bacteria respectively. It

is to be ni'iderstood, however, that the specitic disclosure is for the purpose of exemplitication only, and that the scope of the invention is defined in the following claims in which I have endeavored to distinguish it from the prior art so lar as known to me without, however, relinquishing or abandoning any portion or feature thereof.

' Inthe drawings Figure'l is a longitudinal section of a preferred form of my invention, comprising a form of attachment particularly adapted for counting dust particles; Fig. 2 a transverse section on the line 2 2 of Fig. 1; and Fig. 3 an axial section through an attachment to be used with the device for counting bacteria.

The main element of my dust counter is a pump which is adapted to draw in and discharge a definite i'ueasured quantity oil air, the particular construction thereot being unimportant provided it 't'ultils the above condition. In the particular form shown the pump comprises a barrel lhaving a cap 5 which has an axial bore 6 for the passage of the hollow piston stem 7. The latter has a handle 8 outside the cylinder and at the other end of the piston t) with a packing 10 held betweeii the body o'l said piston and a screw plug it, the flange 12 (Iii which overlaps said packing. The plug 11 has a reduced head .13 through which extends the passage lit and upon which is secured a flexible valve 15 which may be made of 'oiled silk or other suitable material. The intake end of the cylinder is provided with a head 16 per t'o'rated at 1.7 for the passage of air, and extended at .18 to form a seat for the flexible valve 19. The outer end of the cap piece 16 is interiorly threaded at 20'to receive a coupling member 21 which is formed with a nipple 22 to receivean attachment presently to be described. lVhile the form of pump just described is well adapted for the purpose, any othe approved type will'answer provided it is' so constructed that the attaclnnents may be readily mounted thereon, and it is adapted to take in a measured quantity of air.

The attachment to be used for the purpose ot counting dust consists of a casing or chamber (1, the bottom wall 23 being perl'oratcd at 26 in line with the passage 24 of the connection 21, and interioi'ly threaded at 25 to receive the nipple 22. The wall 23 is shouldered and threaded at 27 to receive the cup 28, and the latter is formed with' an axial perforation 29 extending through internal and external bosses 30, 31 formed integral with said cup. \Vithin the chamber post 32 is mounted upon the bottom wal123 and carries a pair of spring arms'33, 33 which, as well as the post, are notched at their ends as at 31,110 receive a thin disk of glass 35, such as are commonly employed as cover plates for microscope slides.

lVhcn the device is to be used for counting dust a glass disk is covered upon one side with a sticky substance which may be Canada balsam, or a mixture of Damar varnish and glycerin, nine parts of the former to oneol the latter.- The disk is then inserted in the support or holder, as shown in the drawing, with the sticky side toward the inlet 29 of the chamber. The pump is then operated to completely till the cylinder thereof. the capacity of which is known. This operation draws in a definite ipuzntity ol air through the opening 29 pro jecting it against the sticky material upon the disk, to which the greater number oi. motes or dust particles in the air adhere. It. may readily be determined by a method hereinafter describei'l what proportion of the entire number ol dust particles in the air arecapturcd by the sticky material on number, the larger the number used the more accurate the results, as will be evident. The external bosses 31 on the chambers are of a size and threaded to'fit the threads 27 in the bottoms of the chambers, thus providin an easy method of mounting the cham er-in series by screwing each successive chamber on the boss of the preceding chamber. When the series of chambers is in place upon the pump and each chamber containing its glass disk coated with. adhesive .the pump is operated todraw in a full charge so that a certain definite amount of air passes successively througheach chamber. The larger proportionofthe motes or solid particles in the air is removed in the first chamber but a certain proportion of the motes escapes, a large proportion of these is caught in the second chamber, and .so on. Obviously by noting the decline in the number of dust particles caught on the succes- .sive disks, by a process of extrapolation 35v the number of particles remaining in the air can be closely approximated and'by adding the results on, the. successive disks the entire number of particles inthe air may be compared with those caught upon the first disk and the efiiciency of the single chamber thus determined. After having made this determination or calibration of theinstrument it isonly necessary thereafter to use a single chamber and by calculation determine the entire number of dust particles per unit of volume in any sample of air.

Preferably an adhesive is used which while rema ning moist or tacky long enough to be properly charged will dry within a convenient length of time retaining .the particlesr It is convenient tomount the disks on the usual microscope slideswith the adhe- .sive containing the dust sealed between the disk and the slide. The countingof course will be done by the aid'of a microscope.

. When the bacteria in a sample of air are to be counted, in place of the glass disk referred to, I use what is known as-a Petrie 601.dish containing a suitable medium for bacteria culture. In Fig. f 3 I have shown a modification of the chamber for the use of the Petrie dish, the only essential modifications being in point of size. The chamber is considerably larger in order to accommo date the Petrie dish 35' and the post 32 and the spring arms 33, 33 are correspondingly modified to form a support for the dish.

For the purpose of counting bacteria the use of the apparatus is identically the same as described in connection with the determinationof dust particles, but I after the pump has drawn the required charge of air through the chamber the culture is incubated at room temperature the requisite length of time and thebacterial colonies that develop are then counted to determine the number of original bacteria caught by the dish. The entire number of colonies may then be calculated as above described in connection with dust counting.

I claim:

1. In a device of the class described, a re ciprocating pump for drawing in and discharging a definite charge of air, a chamber in operative connection with the cylinder of the pump, a support within the chamber and a disk stationarily mounted on the support and having adhesive thereon in the path of thecurrentof air for arresting particles of solid matter. 7

2.. In a device of the class described, a re ciprocating pump for drawing in and discharging a definite charge of air, a chamber detachably mounted on the pump and communicating therewith and with the outer air, and asupport within the chamber for removably holding a disk having adhesive thereon in the line of travel of the air from the inlet to the pump.

3. In a device of the class described, a pump, a chamber detachably mounted on the pump, having communication with the latter, an inlet opposite said communication and a spring support intermediate the inlet and communication for supporting a disk having adhesive thereon in the line of'tra'vel of the air.

4:. In a device of the class described, a

pump, a dust separation chamber comprising a base having means for detachably connecting it to the pump, a'cup detachably I connected to the base and a. support for a disk having sticky matter thereon. mounted in saidchamber. r V

5. In a device of the class described, an air pump adapted to, draw in and discharge a predetermined definite charge of air, a series of chambers connected to the air pump there being series communication between the pump and chambers, such that the charge of air drawn in by the pump passes successively through the chambers, and similar means in each of the chambers for arresting particles of dust contained in the air.

6. In a device of the class described a pump, a dust separation chamber attached to the pump, a disk having sticky matter thereon andmeans detachably supportingsaid disk in the chamber.

7. In a device of the class described, a

pump, a dust separation chamber mounted on the pump and communicating with the cylinder thereof, said chamber having a removable wall, a disk support mounted on said wall, and a disk detachably mounted on said support.

pump, a dust separation chamber attached to said pump and communicating with the cylinder thereof, one of the Walls of said chamber being detachable for access to the 5 interior thereof, means within the chamber for detachably holding a disk, and a disk on said means having adhesive thereon.

8. In a device of the class described a EARL V. HILL.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner 01' Patents. Washington, D. G. 

